1. Field of the Invention
The field of the present invention relates to a disposable dispensing cartridge of the type adapted to be releasably received in an applicator having a movable plunger. More particularly, the field of the present invention is directed to a disposable dispensing cartridge that is especially suitable for dispensing liquid compositions having a relatively low viscosity.
2. Description of the Related Art
A number of dispensing devices are available for dispensing various types of materials. In many instances, the dispensing device is an assembly that includes a reusable dispenser or applicator and a disposable cartridge. The cartridge contains a quantity of a composition or material to be dispensed and is releasably received in a receptacle of the applicator.
In some dispensing assemblies that include an applicator and a cartridge, the applicator has a plunger that is advanced by the user during a dispensing operation. Often, the plunger is received in an open end of the cartridge and bears against a piston within the cartridge. As the plunger is advanced to move the piston, the piston expels a quantity of material through a front outlet opening of the cartridge.
Dispensing devices that include a reusable applicator and a disposable cartridge are favored in many instances, especially in instances where the applicator is relatively expensive in comparison to the cost of the cartridge. For example, many applicators have a movable lever or arm for facilitating advancement of the plunger. Some applicators have a ratchet mechanism associated with the lever for enhancing control over movement of the plunger. Obviously, it is desirable to reuse such applicators in order to reduce costs and avoid disposal issues.
Dispensing devices with disposable cartridges are often used in the field of dentistry for dispensing dental compositions such as restoratives, adhesives, cements, etching gels, sealants and the like. In some instances, the cartridge and the front portion of the applicator receiving the cartridge are relatively small so that the cartridge can be readily maneuvered in the oral cavity during a dispensing operation. In that manner, the dental material contained in the cartridge may be conveniently dispensed directly onto the tooth structure as needed.
Examples of hand-held applicators (also called dispensers or ejector-type guns) that have been used in dentistry are described in U.S. Pat. Nos. 4,198,756, 4,391,590 and 4,472,141. Examples of cartridges (also known as capsules) useful with those applicators are described, for example, in U.S. Pat. Nos. 4,391,590, 4,767,326, 5,100,320 and 5,624,260.
In the field of dentistry, dispensing cartridges are often relatively small and adapted to be used with a single patient. The cartridge is disposed of after the procedure has been accomplished and the applicator is disinfected before use with another cartridge for a subsequent patient. In this manner, the risk of transferring an infectious disease from one patient to another is substantially reduced.
Many of the dental applicators and disposable cartridges that are presently commercially available are used to dispense relatively thick, semi-liquid compositions having a medium or mid-range viscosity ranging from, for example, the viscosity of mayonnaise to a stiff putty. The dental hand-held applicators described in the patents mentioned above include a movable lever that provides a substantial mechanical advantage over movement of the plunger which, in turn, is sufficient to advance the piston in the cartridge and force the composition in the cartridge through a relatively small outlet opening. The substantial mechanical advantage provided by the lever of the applicator is an advantage in those circumstances, because it enables the dental practitioner to dispense the composition directly to a precise location in the oral cavity without undue effort and by use of only one hand.
Unfortunately, the dental applicators and disposable cartridges mentioned in the preceding paragraph are not satisfactory for use in dispensing liquid compositions having a relatively low viscosity such as a viscosity similar to the viscosity of water or milk. In dispensing compositions having relatively low viscosities, the mechanical advantage provided by the applicators mentioned above greatly hinders precise control over the amount of material discharged from the cartridge, since a slight movement of the piston may result in squirting of the composition out of the cartridge. As can be appreciated, such lack of control in dental procedures represents a significant disadvantage that is best avoided.
As a result, it has become common practice for dental practitioners to select some other type of applicator and dispensing method for dispensing dental compositions having a relatively low viscosity. Often, such compositions are dispensed into a mixing well from a squeezable vial, from a syringe or from another type of applicator, such as the applicator shown in applicant's U.S. Pat. No. 5,735,437. In those instances, it is common practice for the practitioner to use a small brush, swab or other similar device to transfer the composition from the mixing well to the patient's dental structures (i.e., the patient's teeth and/or gingiva).
However, the use of the mixing well and brush or swab device as described in the previous paragraph is not entirely satisfactory, in that the steps of dispensing the composition into the well and then transferring the composition from the well to the patient's dental structure is more time-consuming than the act of simply dispensing the liquid composition from a container directly onto the patient's dental structure. Also, there is a risk that the composition may drop off of the brush or swab during convenyance between the well and the dental structure. In addition, the brush or swab device and often the mixing well are intended for use with only a single patient, presenting an issue of disposal. Furthermore, there is a slight risk that the composition may be contaminated and/or contacted by the practitioner while sitting in the open well.
As a consequence, there is a need in the art for a new system that is especially adapted for dispensing precise quantities of compositions having a relatively low viscosity. Preferably, such a system would be useful in the dental arts so that liquid compositions may be dispensed directly onto the teeth and/or gingiva of a dental patient if desired. Moreover, it would be beneficial for such systems to be usable with conventional, well-known applicators so that the operator may dispense the composition and use the applicator with familiar techniques.